[dpdk-dev] [PATCH 3/3] vhost: optimize vhost virtqueue struct

[Xia, Chenbo]

Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Tuesday, December 22, 2020 9:57 PM
> To: dev at dpdk.org; Xia, Chenbo <chenbo.xia at intel.com>; amorenoz at redhat.com
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>
> Subject: [PATCH 3/3] vhost: optimize vhost virtqueue struct
> 
> This patch moves vhost_virtuqueue struct fields in order

s/virtuqueue/virtqueue

> to both optimize packing and move hot fields on the first
> cachelines.

'move hot fields to the first cacheline'? :)

> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> ---
>  lib/librte_vhost/vhost.h | 52 +++++++++++++++++++++-------------------
>  1 file changed, 27 insertions(+), 25 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index e2f14034b4..ce76330d15 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -133,7 +133,7 @@ struct vhost_virtqueue {
>  		struct vring_used	*used;
>  		struct vring_packed_desc_event *device_event;
>  	};
> -	uint32_t		size;
> +	uint16_t		size;
> 
>  	uint16_t		last_avail_idx;
>  	uint16_t		last_used_idx;
> @@ -143,29 +143,12 @@ struct vhost_virtqueue {
>  #define VIRTIO_INVALID_EVENTFD		(-1)
>  #define VIRTIO_UNINITIALIZED_EVENTFD	(-2)
> 
> -	int			enabled;
> -	int			access_ok;
> -	int			ready;
> -	int			notif_enable;
> -#define VIRTIO_UNINITIALIZED_NOTIF	(-1)
> +	bool			enabled;
> +	bool			access_ok;
> +	bool			ready;
> 
>  	rte_spinlock_t		access_lock;
> 
> -	/* Used to notify the guest (trigger interrupt) */
> -	int			callfd;
> -	/* Currently unused as polling mode is enabled */
> -	int			kickfd;
> -
> -	/* Physical address of used ring, for logging */
> -	uint64_t		log_guest_addr;
> -
> -	/* inflight share memory info */
> -	union {
> -		struct rte_vhost_inflight_info_split *inflight_split;
> -		struct rte_vhost_inflight_info_packed *inflight_packed;
> -	};
> -	struct rte_vhost_resubmit_info *resubmit_inflight;
> -	uint64_t		global_counter;
> 
>  	union {
>  		struct vring_used_elem  *shadow_used_split;
> @@ -176,22 +159,36 @@ struct vhost_virtqueue {
>  	uint16_t		shadow_aligned_idx;
>  	/* Record packed ring first dequeue desc index */
>  	uint16_t		shadow_last_used_idx;
> -	struct vhost_vring_addr ring_addrs;
> 
> -	struct batch_copy_elem	*batch_copy_elems;
>  	uint16_t		batch_copy_nb_elems;
> +	struct batch_copy_elem	*batch_copy_elems;
>  	bool			used_wrap_counter;
>  	bool			avail_wrap_counter;
> 
> -	struct log_cache_entry *log_cache;
> +	/* Physical address of used ring, for logging */
>  	uint16_t log_cache_nb_elem;
> +	uint64_t		log_guest_addr;

Looks better to align 'log_cache_nb_elem' with 'log_guest_addr'?

Thanks,
Chenbo

> +	struct log_cache_entry *log_cache;
> 
>  	rte_rwlock_t	iotlb_lock;
>  	rte_rwlock_t	iotlb_pending_lock;
>  	struct rte_mempool *iotlb_pool;
>  	TAILQ_HEAD(, vhost_iotlb_entry) iotlb_list;
> -	int				iotlb_cache_nr;
>  	TAILQ_HEAD(, vhost_iotlb_entry) iotlb_pending_list;
> +	int				iotlb_cache_nr;
> +
> +	/* Used to notify the guest (trigger interrupt) */
> +	int			callfd;
> +	/* Currently unused as polling mode is enabled */
> +	int			kickfd;
> +
> +	/* inflight share memory info */
> +	union {
> +		struct rte_vhost_inflight_info_split *inflight_split;
> +		struct rte_vhost_inflight_info_packed *inflight_packed;
> +	};
> +	struct rte_vhost_resubmit_info *resubmit_inflight;
> +	uint64_t		global_counter;
> 
>  	/* operation callbacks for async dma */
>  	struct rte_vhost_async_channel_ops	async_ops;
> @@ -210,6 +207,11 @@ struct vhost_virtqueue {
>  	bool		async_inorder;
>  	bool		async_registered;
>  	uint16_t	async_threshold;
> +
> +	int			notif_enable;
> +#define VIRTIO_UNINITIALIZED_NOTIF	(-1)
> +
> +	struct vhost_vring_addr ring_addrs;
>  } __rte_cache_aligned;
> 
>  /* Virtio device status as per Virtio specification */
> --
> 2.29.2